Package org.eclipse.swt.dnd

Class ByteArrayTransfer

java.lang.Object
org.eclipse.swt.dnd.Transfer
org.eclipse.swt.dnd.ByteArrayTransfer
Direct Known Subclasses:
FileTransfer, HTMLTransfer, ImageTransfer, RTFTransfer, TextTransfer, URLTransfer
public abstract class ByteArrayTransfer extends Transfer
The class ByteArrayTransfer provides a platform specific mechanism for converting a java byte[] to a platform specific representation of the byte array and vice versa.

ByteArrayTransfer is never used directly but is sub-classed by transfer agents that convert between data in a java format such as a String and a platform specific byte array.

If the data you are converting does not map to a byte[], you should sub-class Transfer directly and do your own mapping to a platform data type.

The following snippet shows a subclass of ByteArrayTransfer that transfers data defined by the class MyType.


 public class MyType {
        public String fileName;
        public long fileLength;
        public long lastModified;
 }
 

 public class MyTypeTransfer extends ByteArrayTransfer {
        
        private static final String MYTYPENAME = "my_type_name";
        private static final int MYTYPEID = registerType(MYTYPENAME);
        private static MyTypeTransfer _instance = new MyTypeTransfer();
 
 private MyTypeTransfer() {}
 
 public static MyTypeTransfer getInstance () {
        return _instance;
 }
 public void javaToNative (Object object, TransferData transferData) {
        if (object == null || !(object instanceof MyType[])) return;
        
        if (isSupportedType(transferData)) {
                MyType[] myTypes = (MyType[]) object;   
                try {
                        // write data to a byte array and then ask super to convert to pMedium
                        ByteArrayOutputStream out = new ByteArrayOutputStream();
                        DataOutputStream writeOut = new DataOutputStream(out);
                        for (int i = 0, length = myTypes.length; i < length;  i++){
                                byte[] buffer = myTypes[i].fileName.getBytes();
                                writeOut.writeInt(buffer.length);
                                writeOut.write(buffer);
                                writeOut.writeLong(myTypes[i].fileLength);
                                writeOut.writeLong(myTypes[i].lastModified);
                        }
                        byte[] buffer = out.toByteArray();
                        writeOut.close();
 
                        super.javaToNative(buffer, transferData);
                        
                } catch (IOException e) {
                }
        }
 }
 public Object nativeToJava(TransferData transferData){ 
 
        if (isSupportedType(transferData)) {
                
                byte[] buffer = (byte[])super.nativeToJava(transferData);
                if (buffer == null) return null;
                
                MyType[] myData = new MyType[0];
                try {
                        ByteArrayInputStream in = new ByteArrayInputStream(buffer);
                        DataInputStream readIn = new DataInputStream(in);
                        while(readIn.available() > 20) {
                                MyType datum = new MyType();
                                int size = readIn.readInt();
                                byte[] name = new byte[size];
                                readIn.read(name);
                                datum.fileName = new String(name);
                                datum.fileLength = readIn.readLong();
                                datum.lastModified = readIn.readLong();
                                MyType[] newMyData = new MyType[myData.length + 1];
                                System.arraycopy(myData, 0, newMyData, 0, myData.length);
                                newMyData[myData.length] = datum;
                                myData = newMyData;
                        }
                        readIn.close();
                } catch (IOException ex) {
                        return null;
                }
                return myData;
        }
 
        return null;
 }
 protected String[] getTypeNames(){
        return new String[]{MYTYPENAME};
 }
 protected int[] getTypeIds(){
        return new int[] {MYTYPEID};
 }
 }
Since:
1.3
See Also:

  • Constructor Details

    • ByteArrayTransfer

      public ByteArrayTransfer()

  • Method Details

    • getSupportedTypes

      public TransferData[] getSupportedTypes()
      Description copied from class: Transfer
      Returns a list of the platform specific data types that can be converted using this transfer agent.

      Only the data type fields of the TransferData objects are filled in.

      Specified by:
      getSupportedTypes in class Transfer
      Returns:
      a list of the data types that can be converted using this transfer agent

    • isSupportedType

      public boolean isSupportedType(TransferData transferData)
      Description copied from class: Transfer
      Returns true if the TransferData data type can be converted using this transfer agent, or false otherwise (including if transferData is null).
      Specified by:
      isSupportedType in class Transfer
      Parameters:
      transferData - a platform specific description of a data type; only the data type fields of the TransferData object need to be filled in
      Returns:
      true if the transferData data type can be converted using this transfer agent

    • javaToNative

      public void javaToNative(Object object, TransferData transferData)
      This implementation of javaToNative converts a java byte[] to a platform specific representation.
      Specified by:
      javaToNative in class Transfer
      Parameters:
      object - a java byte[] containing the data to be converted
      transferData - an empty TransferData object that will be filled in on return with the platform specific format of the data
      See Also:

    • nativeToJava

      public Object nativeToJava(TransferData transferData)
      This implementation of nativeToJava converts a platform specific representation of a byte array to a java byte[].
      Specified by:
      nativeToJava in class Transfer
      Parameters:
      transferData - the platform specific representation of the data to be converted
      Returns:
      a java byte[] containing the converted data if the conversion was successful; otherwise null
      See Also: